接口核心流程
- java
- 1.建立Dynamic Web Project项目(javaweb)
- 2.创建-包-servlet
- [ ] 3.javaweb加入头部开启跨域
response.setHeader("Access-Control-Allow-Origin", "*");
- 4.请求
- doget 写get请求
- [ ] 接取数据库信息
- [ ] 转成json形式
- 传到前台
- dopost 写post请求
- doget 写get请求
- web
- 调取接口
- error问题
dataType: "json"//传值类型不对就算成功接取数据也会返回error
1.eclipse 创建项目
Dynamic Web Project
- 创建servlet
图片
package com.niu;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class ServletTest
*/
@WebServlet("/ServletTest")
public class ServletTest extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public ServletTest() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
//response.getWriter().append("Served at: ").append(request.getContextPath());
response.setHeader("Access-Control-Allow-Origin", "*");
response.setHeader("Content-type", "text/html;charset=UTF-8");
response.setCharacterEncoding("UTF-8");
/** * 当多线程并发访问这个方法里面的代码时，会存在线程安全问题吗
* * i变量被多个线程并发访问，但是没有线程安全问题，因为i是doGet方法里面的局部变量，
* * 当有多个线程并发访问doGet方法时，每一个线程里面都有自己的i变量， 各个线程操作的都是自己的i变量，所以不存在线程安全问题
* * 多线程并发访问某一个方法的时候，如果在方法内部定义了一些资源(变量，集合等) 那么每一个线程都有这些东西，所以就不存在线程安全问题了
* */
String text = (String) request.getParameter("text");
System.out.println("结果已经传入后台：" + text);
String output = "后台返回的结果加上前台的结果" + text;
response.getWriter().write(output);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
package com.runoob.test;
import java.io.PrintWriter;
import java.sql.*;
import java.util.*;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import net.sf.json.JSONArray;
/**
* Servlet implementation class DatabaseAccess
*/
@WebServlet("/DatabaseAccess")
public class DatabaseAccess extends HttpServlet {
private static final long serialVersionUID = 1L;
// JDBC 驱动名及数据库 URL
static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://localhost:3306/myigou?useSSL=false";
// 数据库的用户名与密码，需要根据自己的设置
static final String USER = "root";
static final String PASS = "23629423";
/**
* @see HttpServlet#HttpServlet()
*/
public DatabaseAccess() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
Connection conn = null;
Statement stmt = null;
// 设置响应内容类型
response.setHeader("Access-Control-Allow-Origin", "*");
response.setContentType("text/html;charset=UTF-8");
try{
// 注册 JDBC 驱动器
Class.forName(JDBC_DRIVER);
// 打开一个连接
conn = DriverManager.getConnection(DB_URL,USER,PASS);
// 执行 SQL 查询
stmt = conn.createStatement();
String sql;
sql = "SELECT address_id, addressinfo, addressarea FROM address";
ResultSet rs = stmt.executeQuery(sql);
JSONArray jsonData = JSONArray.fromObject(convertList(rs));
System.out.println(jsonData.toString());
PrintWriter out = response.getWriter(); //把json数据传递到前端，记着前端用ajax接收
out.print(jsonData);
// response.getWriter().write(rs);
// 展开结果集数据库
/*while(rs.next()){
// 通过字段检索
// 通过字段检索
int id = rs.getInt("address_id");
String name = rs.getString("addressinfo");
String url = rs.getString("addressarea");
// 输出数据
out.println("ID: " + id);
out.println(", 站点名称: " + name);
out.println(", 站点 URL: " + url);
out.println("
");
}*/
/*out = response.getWriter();
*/
// 完成后关闭
rs.close();
stmt.close();
conn.close();
} catch(SQLException se) {
// 处理 JDBC 错误
se.printStackTrace();
} catch(Exception e) {
// 处理 Class.forName 错误
e.printStackTrace();
}finally{
// 最后是用于关闭资源的块
try{
if(stmt!=null)
stmt.close();
}catch(SQLException se2){
}
try{
if(conn!=null)
conn.close();
}catch(SQLException se){
se.printStackTrace();
}
}
}
// ResultSet rs 转json
private static List convertList(ResultSet rs) throws SQLException {
List list = new ArrayList();
ResultSetMetaData md = rs.getMetaData();
int columnCount = md.getColumnCount();
while (rs.next()) {
Map rowData = new HashMap();
for (int i = 1; i <= columnCount; i++) {
rowData.put(md.getColumnName(i), rs.getObject(i));
}
list.add(rowData);
}
return list;
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
3.编写xml
图片
gitTest
index.html
index.htm
index.jsp
default.html
default.htm
default.jsp
default
org.apache.catalina.servlets.DefaultServlet
debug
0
listings
false
1
ServletDemo1
com.niu.ServletTest
ServletDemo1
/ajaxtest
4.项目内ajax调取接口
测试用例
测试例子
5.项目外调取接口
Document